/**
 * @class 监听虚拟键盘
 * @classdesc 监听虚拟键盘弹出隐藏
 * @public onEnd 结束监听虚拟键盘
 * @public onShow 传递一个回调 监听虚拟键盘弹出
 * @public onHidden 传递一个回调 监听虚拟键盘隐藏
 */
 class MonitorKeyboard {
  constructor() {
    this.type = this.IsIA();
    this.originalHeight = window.innerHeight;
  }
 
  /**
   *  @function IsIA 获取设备类型
   *  @param  1 Android 2 iOS  
   */
  IsIA = () => {
    const userAgent = typeof window === 'object' ? window.navigator.userAgent : '';
    if (/android/i.test(userAgent)) {
      return 1; 
    } else if (/iPhone|iPod|iPad/i.test(userAgent)) {
      return 2; 
    }
  }

  // Android系统
  onResize = () => {
    //键盘弹起与隐藏都会引起窗口的高度发生变化
    const resizeHeight = window.innerHeight;

    if (this.originalHeight - resizeHeight > 50) {
      this.show('Android系统: 软键盘弹出');
    } else {
      this.hidden('Android系统: 软键盘收起');
    }
  }

  // iOS获取焦点
  onFocusin = () => {
    this.show('iOS系统:软键盘弹出');
  }
 
  // iOS失去焦点
  onFocusout = () => {
    this.hidden('iOS系统:软键盘收起');
  }

  /**  
   * @function onStart 开始监听虚拟键盘  
   */
  onStart = () => {
    if (this.type == 1) {
      // 获取窗口的高度
      window.addEventListener('resize', this.onResize);
    }
    if (this.type == 2) {
      // iOS系统
      window.addEventListener('focusin', this.onFocusin);
      window.addEventListener('focusout', this.onFocusout);
    }
  }
 
  /** 
   * @function onEnd 结束监听虚拟键盘  
   */
  onEnd = () => {
    if (this.type == 1) {
      //获取窗口的高度
      window.removeEventListener('resize', this.onResize);
    }
    if (this.type == 2) {
      window.removeEventListener('focusin', this.onFocusin);
      window.removeEventListener('focusout', this.onFocusout);
    }
  }
 
  /**
   * @function  onShow 传递一个回调函数
   * @param  虚拟键盘弹出时触发
   */
  onShow = (fn) => {
    this.show = fn;
  }
   
  /**
    * @function  onHidden 传递一个回调函数
    * @param  虚拟键盘隐藏时触发
    */
  onHidden = (fn) => {
    this.hidden = fn;
  }
}
 
export default MonitorKeyboard
